val in self.channels.items() can be float

Hi fellow,

thanks a looot for your library. Real nice work.

I ran into an issue (can't tell you the origin), but by using a constant stream following line in _Controller.py might create a float, which later on will crash the program:

# Get all channels values
               for key, val in self.channels.items():
                    # If channel in frame
                    if key - first < len(self.__frame):
                       self.__frame[key - first] = int(val[0])`

i placed an int() around the val[0]. Not sure if that's in general a good idea.

but it fixed the issue, that otherwise at this call would break the runtime.

def _transmit(self, frame: List[int], first: int):
        # Convert to a bytearray and pad the start of the frame
        # We're transmitting direct DMX data here, so a frame must start at channel 1, but can end early
        try:
            data = bytearray(([0] * (first - 1)) + frame)
            # The first byte in the type, and is `0` for normal DMX data
            data.insert(0, 0)

            # Write
            self.__device.send_break(100e-6)
            sleep(10e-6)
            self.__device.write(data)
        except:
            print("bad request")`
```

as you see I made a try / except for myself.

Commencez dans _Controller.py, au niveau de la boucle des valeurs de canal, et examinez comment les valeurs de self.channels.items() parviennent jusqu’à _transmit. Reproduisez le cas d’un flux constant qui produit un float, puis vérifiez que le traitement choisi préserve des données de trame DMX valides et empêche l’échec de la conversion en bytearray.